Spray nozzle



Oct. 3, 1950 T. F. BARR ETAL SPRAY NOZZLE 2 Sheets-Sheet 1 Filed June 4, 1949 22 INVENTORS THEODORE F. BARR AND CLIFFORD w. DOUGHMAN THEIR ATTOR N EY Oct. 3, 1950 T. F. BARR ETAL 2,524,097

SPRAY NOZZLE Filed June 4, 1949 2 Sheets-Sheet 2 INVENTORS N. O THEODORE F. BARR AND I CLIFFORD W. DOUGHMAN THEIR ATTORNEY Patented Oct. 3, 1950 SPRAY NOZZLE Theodore F. Barr and Clifford W. Doughman, Dayton, Ohio, assignors to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland Application June 4, 1949, Serial N 0. 97,196

Claims.

This invention relates to improvements in the construction of vapor blast nozzles for producing a wide curtain spray of uniform density.

Vapor blast processes are used to make the surfaces of metal parts metallurgically clean, prior to electro-plating and for producing certain finishes. To produce an even finish over the entire surface of the metal of wide dimensions, it is necessary to produce a vapor spray of an abrasive mixture in the form of a curtain extending over the entire width of the part so that no overlapping is produced. In the nozzles known in the prior art, the width of the spray produced was so limited that only a narrow curtain could be produced, resulting in finishes that were not uniform in prepared work of dimensions wider than the width of the curtain.

It is therefore an object of the invention to provide a vapor spray nozzle for producing a wide curtain spray of abrasive mixture.

A specific object of the invention is to provide a vapor spray nozzle mixture chamber and an air chamber adjustable relatively therein to provide a curtain spray.

Another object of the invention is to provide outlet slots for an air chamber and a mixture chamber constructed and correlated in relation with each other so as to produce a wide and uniform curtain spray.

With these and incidental objects in view, the

invention includes certain novel features of construction and combinations of parts, preferred forms or embodiments of which are hereinafter described with reference to the drawings which accompany and form a part of this specification.

0f said drawings:

Fig. l is a sectional view through the nozzle, taken on line II of Fig. 4, and looking in the direction of the arrow.

Fig. 2 is a bottom view of the nozzle.

Fig. 3 is a detailed sectional view of a modified form of nozzle throat.

Fig. 4 is a longitudinal cross-sectional view taken on line 44 of Fig. 1 and looking in the direction of the arrows.

General description In use, parts madeof metal which are plated and highly polished (such as, for example, chromium finishes) upon being handled soon become unsightly from finger prints or other blemishes. To avoid this, and/or to produce a satin-like finish, the metal parts are first processed by slightly abrading the surface. Thereafter, when such parts are plated, a Satinlike finish is produced. One problem in abrading such parts in the prior art was that, in performing the abrading operations, streaks, or other blemishes, would appear, which were due to the requirement that the parts had to be sent through the spray two or more times, in those cases where the parts had a dimension wider than the width of the curtain spray produced by conventional spray nozzles.

To overcome the objections to conventional nozzles, applicants have provided a nozzle in which an air outlet is located in respect to an abrasive mixture outlet to provide a uniform curtain of any desired width. By way of illustration, the nozzle is herein disclosed to produce a curtain approximately five and one-half inches wide when located five inches from the work to be processed. In processing the surface of the work, the work is fed through the spray curtain at a steady rate of speed, the rate being determined by the finish desired.

Detailed description A mixture chamber In is formed by using a tubular member I I, which member may be a piece of standard pipe, threaded at each end to receive caps I2. The tubular member II is slotted to form an opening to receive plates I3 and I4, which are brazed, or welded, to the two sides of the opening. Shoes I5 and iii are accurately machined and attached to the plates I3 and II, respectively, by screws I I and I8. The shoes I5 and I6 may be made of any suitable abrasionresistant material, such as tempered metal or rubber, the latter giving excellent wearing qualities. Retaining plates I9 and 20 are mounted on the plates I3 and I4, respectively, to retain the shoes I5 and I6 in position. End walls 22 are secured to the plates I3 and M to form closures at each end of a slot 23 formed by shoes I5 and I6. Two hoppers 24, of at least the length of the slot 23, are provided, having narrow openings 25 leading abrasive mixture into the mixture chamber I0. Suitable slits are cut into the pipe I I to receive the lower ends of the hopper in such a location that the mixture will form a curtain and fall on the surfaces 26 of the plates I3 and I4. Experiment has shown that, in a spray nozzle of the dimensions shown herein, the shoes I5 and I6 should be provided with rounded corners 21, and that the radii of the corners 21 should be approximately five-sixteenths of an 'inch for best results.

Mounted within the mixture chamber I0 is an air chamber 30, which chamber is constructed from a tubular piece such as a pipe 3|, closed at each end by plugs 32, threaded to enter inside threads in the pipe 3|. Openings 33 to fit an end wrench form one method of tightening the plugs 32 in the ends of the pipe 31.

The pipe 3| is slotted to receive two shoes 34, which are machined and brazed, or otherwise securely fastened therein, so as to be air-tight. The shoes 34, after being mounted in the pipe 3!, form an air jet slot 35 to guide compressed air through the slot 23, to vaporize the abrasive mixture in the chamber Ill and to force the vaporized mixture therethrough. The walls of the air jet slot 35 must be parallel at least one-eighth of an inch long and machined extremely smooth. The air jet slot 35 must also be in exact alinement with the abrasive mixture slot 23 to operate the nozzle successfully.

Mounted, so as to be in exact alinement with the air jet slot 35, are a plurality of air intake pipes 36. As illustrated herein, four pipes 35 are shown, which are suiiicient for a nozzle intended to form a curtain of vapor five and one-half inches wide. The number of pipes to be used will vary with the width of the curtain to be formed.

A dispersion rod 40 is freely mounted in the caps 32 'in the center of the air chamber 30 to properly disperse the air forced through the pipes 36. To provide a solid connection to the pipe 3i for the pipes 36, a bar 31 is brazed to the pipe 3|, both of which are drilled and tapped to receive the pipes 36 as shown.

The spacing of the air jet slot 35 from the abrasive mixture slot 23 is critical for best results.

To enable the operator to get the best spacing between the two slots, the assembly including the pipe 3!, the shoes 34, and the pipes 36 is adjustably mounted in the mixture chamber Ill. To provide for such adjustment, the pipes 35 are slidably mounted in a plate 38 brazed to the tubular member H. Set screws 33 provide a means to maintain the adjustable unit in the proper position;

A modified form of the throat construction is shown in Fig. 3, where the shoes I5 and I6 are replaced by rotatably mounted rods 56. The rods 56 are provided with reduced ends to fit bearings in the walls 22. For best results, it has been found that the rods should be made from fiveeighths-inch diameter stock.

While the forms of mechanism herein shown and described are admirably adapted to fulfill the objects primarily stated, it is to be understood that it is not intended to confine the invention to the two forms or embodiments disclosed herein, for it issusce'ptible of embodiment in various other forms. 7

What is claimed is:

1. In a vapor spray nozzle, the combination of a plurality of hoppers having outlet openings constructed to release a curtain of abrasive mixture therefrom, a mixing chamber into which said curtain of mixture is released, an air jet chamber adjustably mounted within the mixing chamber, a dispersion means freely mounted in the center of the air jet chamber to disperse the air in the air jet chamber, a plurality of air conduits to supply compressed air to the air jet chamber, an outlet from the air jet chamber consisting of a narrow slot, andan outlet from the mixing chamber in exact alinement with the outlet from the air jet chamber, whereby the air forced through the first-named outlet atomizes the abrasive mixture and forces the mixture through the secondnamed outlet to form a vapor curtain.

2. In a vapor spray nozzle, the combination of hoppers, each having an outlet opening at the bottom thereof of widths equal to the width of the hoppers to release curtains of abrasive mixture therefrom, a mixing chamber into which said curtains of mixture are released, an air jet chamber mounted within the mixing chamber, a dispersion means rotatably mounted in said air jet chamber to disperse the air in the air jet chamber, a plurality of air conduits through which compressed air is supplied to the air jet chamber, a narrow slot in the air jet chamber, and a slot located in the mixing chamber in exact alinement with the slot in the air jet chamber, where- .by compressed air is guided from the air jet chamber through the abrasive mixture and the slot in the mixture chamber to form a vapor curtain.

3. In a vapor spray nozzle, the combination of hoppers, each having an outlet opening at the bottom thereof of widths equal to the width of the hoppers to release curtains of abrasive mixture therefrom, a mixing chamber into which said curtains of mixture are released, an air jet chamber within the mixing chamber equal in width to the inside width of the mixing chamber, a dispersion means consisting of a rod rotatably mounted in said air jet chamber to disperse the air in the air jet chamber, a plurality of air conduits through which compressed air is supplied to the air jet chamber, a narrow slot in the air jet chamber, and a slot located in the mixing chamber in exact alinement with the slot in the air jet chamber, whereby compressed air is guided from the air jet chamber through the abrasive mixture and the slot in the mixing chamber to form a, vapor curtain.

4. In a vapor spray nozzle, the combination of hoppers, each having an outlet opening at the bottom thereof of widths equal to the width of the hoppers to release curtains of abrasive mixture therefrom, a mixing chamber into which said ourtains of mixture are released, an air jet chamber within the mixing chamber equal in width to the inside width of the mixing chamber, a dispersion means rotatably mounted in said air jet chamber to disperse the air in the air jet chamber, a plurality of airconduits through which compressed air is supplied to the air jet chamber, a narrow slot extending the full width of the air jet chamber, and a slot located in the mixing chamber in exact alinement with the slot in the air jet chamber, whereby compressedair is guided from the air jet chamber through the abrasive mixture and the slot in the mixing chamber to form a vapor curtain.

5. In a vapor spray nozzle, the combination of hoppers, each having an outlet opening at the bottom thereof of widths equal to the width of the hoppers to release curtains of abrasive mixture therefrom, a mixing chamber into which said curtains of mixture are released,-an air jet chamber within the mixing chamber equal in width to the inside width of the mixing chamber, a dispersion means rotatably mounted in said air jet chamber to disperse the air in the air .jet chamber, a plurality of air conduits through which compressed air is supplied to the air jet chamber, a narrow slot extending the full width of the air jet chamber, and a slot in the mixing chamber equal in width to the slot in the. air jet chamber and in exact alinement therewith, whereby compressed air is guided from the air jet chamber through the abrasive mixture and the slot in the mixing chamber to form a vapor curtain, the adjacent inner corners of the walls forming the slot in the mixing chamber being rounded. 5

THEODORE F. BARR. CLIFFORD W. DOUGHMAN.

REFERENCES CITED The following references are of record in the 10 file of this patent:

Number Number 6 UNITED STATES PATENTS Name Date Mathewson Aug. 27, 1889 Weyl Jan. 19, 1915 Fulton Apr. 25, 1933 FOREIGN PATENTS Country Date Switzerland Mar. 1, 1920 

